Combination Dextromethorphan, Sitagliptin Shows Promise for Diabetes

(HealthDay News) — Dextromethorphan combined with sitagliptin shows potential for treatment of type 2 diabetes, according to a study published in Diabetes, Obesity and Metabolism.

Jan Marquard, MD, from Heinrich Heine University in Germany, and colleagues examined the blood-glucose-lowering effects of 30 mg, 60 mg and 90 mg dextromethorphan as well as 100 mg sitagliptin alone vs. combinations of dextromethorphan and sitagliptin during an oral glucose tolerance test (OGTT). Participants consisted of 20 men with type 2 diabetes.

Results reveal that the strongest effect in the OGTT was seen with the combination of 60 mg dextromethorphan plus 100 mg sitagliptin. Maximum blood glucose concentrations were lowered with this combination. 

In addition the baseline-adjusted area under the curve of serum insulin concentrations was increased in the first 30 minutes of the OGTT to a significantly larger extent than with 100 mg sitagliptin alone (P<.05) or placebo (P<.001). 

All study drugs, alone or in combination, were tolerated, with no evidence of serious adverse events or hypoglycemia.

“Long-term clinical trials are now warranted to investigate the potential of the combination of 30 or 60 mg dextromethorphan and dipeptidyl peptidase-4 inhibitors in the treatment of individuals with type 2 diabetes mellitus, in particular since preclinical studies revealed beta cell protective properties of dextromethorphan,” the researchers wrote.

Three study researchers are pursuing a patent titled “Morphinan-derivatives for treating diabetes and related disorders.”


  1. Marquard J et al. Diabetes Obes Metab. 2015;doi:10.1111/dom.12576.